Ideal Weight Calculator

How This Calculator Works

Our ideal weight calculator uses four well-established medical formulas to estimate a healthy target weight based on your height and gender. Each formula was developed by different researchers and produces slightly different results, giving you a realistic range to aim for rather than a single arbitrary number.

The calculator also factors in body frame size. People with larger frames naturally carry more lean mass and bone density, so their ideal weight is adjusted upward by roughly 10%. Conversely, those with smaller frames see a 10% reduction. This accounts for the significant variation in body composition between individuals of the same height.

Steps to use:

1. Select your preferred unit system (imperial or metric)
2. Enter your height in feet and inches or centimeters
3. Select your gender
4. Choose your body frame size (small, medium, or large)
5. View results from all four formulas instantly

The Four Ideal Weight Formulas

Each formula below estimates ideal body weight in kilograms. Heights are converted to inches internally. The term “height over 60 inches” refers to the number of inches your height exceeds 5 feet (60 inches).

Devine Formula (1974)

Developed by Dr. B.J. Devine, this is the most widely used formula in clinical settings and pharmaceutical dosing. It is the basis for many drug dosage calculations.

Men:   IBW = 50 kg + 2.3 kg per inch over 5 feet Women: IBW = 45.5 kg + 2.3 kg per inch over 5 feet

Robinson Formula (1983)

Dr. J.D. Robinson modified Devine's formula after finding that Devine's estimates tended to be too low for women and too high for taller men.

Men:   IBW = 52 kg + 1.9 kg per inch over 5 feet Women: IBW = 49 kg + 1.7 kg per inch over 5 feet

Miller Formula (1983)

Dr. D.I. Miller proposed this formula based on a larger and more diverse dataset than previous studies. It tends to give slightly higher estimates for shorter individuals.

Men:   IBW = 56.2 kg + 1.41 kg per inch over 5 feet Women: IBW = 53.1 kg + 1.36 kg per inch over 5 feet

Hamwi Formula (1964)

Dr. G.J. Hamwi introduced this formula as a simple rule of thumb for clinical use. It allows for quick mental calculation and was widely adopted in nutrition counseling.

Men:   IBW = 48 kg + 2.7 kg per inch over 5 feet Women: IBW = 45.5 kg + 2.2 kg per inch over 5 feet

Understanding Body Frame Size

Body frame size reflects your skeletal structure and natural build. Two people of the same height can have meaningfully different ideal weights depending on their frame. A simple way to estimate your frame size is to wrap your thumb and middle finger around your wrist:

• Small frame: Your fingers overlap when gripping your wrist
• Medium frame: Your fingers just touch
• Large frame: Your fingers do not touch

This calculator applies a 10% adjustment for small and large frames. For a medium frame, no adjustment is made. Keep in mind that frame size is a rough approximation, and the actual adjustment for an individual may vary.

Healthy BMI Weight Range

The calculator also displays the weight range that corresponds to a healthy Body Mass Index (BMI) of 18.5 to 24.9 for your given height. This range is derived from the standard BMI formula:

BMI = weight (kg) / height (m)² Weight = BMI × height (m)²

For example, a person who is 170 cm tall has a healthy weight range of approximately 53.5 kg to 72.0 kg. Your ideal weight from the formulas above should fall within or near this range. If your formula results are well above the BMI range, it may indicate that the formulas overestimate for your particular build.

Limitations of Ideal Weight Formulas

Ideal weight formulas are useful guidelines, but they have important limitations. They were developed primarily from data on Caucasian populations and may not be equally accurate for all ethnic groups. They also do not account for age, muscle mass, body fat percentage, or overall health status.

• Age: As people age, they naturally lose muscle mass and gain fat. A healthy weight at 60 may differ from one at 25.
• Muscle mass: Athletes and those who strength train carry more muscle, which weighs more than fat. Their “ideal” weight by these formulas may be unrealistically low.
• Body composition: Two people at the same weight can have very different health profiles depending on their ratio of fat to lean tissue.
• Ethnicity: Research suggests that optimal BMI thresholds may vary by ethnicity. For instance, some Asian populations may face health risks at lower BMI values.

Always consult with a healthcare professional for personalized weight guidance. These formulas are best used as a starting point for discussion, not as definitive medical advice.

Frequently Asked Questions

Which ideal weight formula is the most accurate?

No single formula is universally more accurate. The Devine formula is the most commonly used in clinical practice and drug dosing. The Robinson and Miller formulas are considered improvements over Devine. In practice, looking at the range across all four formulas gives a more realistic picture than relying on any single one.

How do I determine my body frame size?

The simplest method is the wrist test: wrap your thumb and middle finger around the narrowest part of your wrist. If your fingers overlap, you have a small frame. If they just touch, your frame is medium. If there is a gap, your frame is large. Alternatively, measure your wrist circumference: under 6.5 inches (women) or 7 inches (men) suggests a small frame.

Why do the formulas give different results?

Each formula was developed by different researchers using different study populations and statistical methods. Some prioritize simplicity (Hamwi), others aim for statistical accuracy across broader height ranges (Miller). The variation between formulas typically ranges from 5% to 15%, which reflects the natural variation in healthy body weight.

Is ideal weight the same as a healthy weight?

Not exactly. Ideal weight is a statistical estimate based on height and gender. A healthy weight also depends on body composition (muscle vs. fat), age, activity level, and metabolic health. Someone with significant muscle mass may weigh well above their “ideal” weight and still be perfectly healthy.

Can I use this calculator for children or teenagers?

No. These formulas were designed for adults and are not appropriate for growing children or teenagers. Pediatric growth charts and BMI-for-age percentiles are the appropriate tools for assessing weight in younger populations. Consult a pediatrician for guidance on your child's weight.

How does ideal weight relate to BMI?

BMI (Body Mass Index) is a separate metric that relates weight to height. A BMI between 18.5 and 24.9 is considered normal weight. The calculator shows the weight range corresponding to this healthy BMI for your height. Your ideal weight from the formulas should generally fall within or near this range.